Field of the Invention
The present disclosure pertains to valve, more specifically to valves wherein hydraulic fluid pressure is used to set the positioning of the valve components as between the open and the closed states.
Description of the Related Art
Check valves are used in many applications to control the pressure at or in a hydraulic component. In prior art check valves used in oil and gas production, such as in the control circuits used to hydraulically control fluid flow and pressure among various hydraulically controlled and/or operated components, the selective communication of fluid across the check valve comprises the use of a ball which is spring loaded against a seat. A spring guide is held in place in the outlet bore of the check valve with a snap ring, and a seat, having an opening therein, is located in the outlet bore at a location where the inlet bore meets and communicates with the outlet bore. The ball is disposed in the outlet bore between the spring guide and the seat, and is biased by the spring against a conical or spherical sealing surface surrounding the opening in the seat. The spring is unguided in the space between the end of the spring guide and the ball. When the pressure in the outlet bore is sufficiently less than that in the inlet bore, the force of the spring biasing the ball against the seat is overcome, and the ball is pushed off of the seat and fluid flows through the annular opening between the ball and the adjacent sealing surface of the seat. Again, unless the pressure difference is great, and fluid flow through the annulus formed between the ball and sealing surface is large, the ball will not become grounded against the end of the spring guide, and the ball can wobble within the outlet bore, and is known to rotate in the outlet bore. The wobbling and rotating of the ball causes wear on the ball and the adjacent end of the spring, and the ball can separate laterally from the end of the spring, causing the spring to bind or break. Additionally, the snap ring has been known to fail, which causes the check valve to fail in an open condition.
Additionally, piloted check valves are known, wherein the valve includes a third, control fluid bore connected to a source of control fluid, which is used to selectively bias the end of a pin inserted into a piston against the ball if there is a need to open communication between the outlet and inlet when the pressure difference therebetween is insufficient to open the valve. This occurs, for example, when the outlet pressure exceeds the inlet pressure and there is a desire to vent an overpressure condition in the outlet bore.